The invention relates to a cooling system with indirect charge air cooling. Cooling systems of this type are used, for example, for motor vehicle engines having turbochargers, in order to use the general cooling circuit to cool the engine and the additional cooling circuit to indirectly cool the charge air which is supplied to the engine by the turbocharger. The invention also relates to a cooling system for a motor vehicle with direct charge air cooling. Cooling systems of this type are used, for example for motor vehicle engines with turbochargers, in order to use the general cooling circuit for the cooling of the engine and the additional cooling circuit for indirectly cooling the charge air which is supplied to the engine by the turbocharger.
The use of a cooling system for cooling the engine and for indirect charge air cooling in a motor vehicle is described in a paper entitled “Coolant-cooled charge air cooler for motor vehicle engines”, published in the journal MTZ Motortechnische Zeitschrift 61(2000)9, pages 592 to 599. In the system described therein, the means for regulating the coolant flow through the main coolant cooler and the means for sensing the coolant temperature are integral parts of a thermostat element, which is arranged upstream of the main coolant cooler at a branching point of a bypass line bypassing the main coolant cooler. The additional cooling circuit including the additional coolant cooler, which is referred to in this application as the low-temperature coolant cooler, branches off between the engine and the thermostat from the general cooling circuit, with a regulating valve being arranged upstream of the low-temperature coolant cooler. After passing through the low-temperature coolant cooler, the coolant flows via the general cooling circuit to a charge air cooler and is then returned again to the general cooling circuit at an input point situated between the main coolant cooler and a coolant circulating pump. The bypass line bypassing the main coolant cooler also joins in at this input point.
It is the object of the present invention to provide a cooling system of the type mentioned initially which can be realized with comparatively little outlay and which facilitates reliable control of the coolant flow.
It is particularly the object of the present invention to provide a cooling system, which, with comparatively little outlay, facilitates the temperature of the coolant conducted through the additional coolant circuit to be taken into consideration in the control of the coolant flow and which provides for a sufficient pressure differential for the additional cooling circuit but the pressure load on the additional coolant cooler remains relatively low.